Process of obtaining zinc solutions free from iron and manganese compounds.



. tory furnace or a mu After it has been withdrawn from the UNITEDSTATES PATENT OFFICE.

FRIEDRICH AUGUST GASCH, OF HCNNINGEN-ON-THE-RHINE, GERMANY.

PROCESS OF OBTAINING ZINC SOLUTIONS FREE FROM IRON AND MANGANESECOMPOUNDS.

SPECIFICATION forming part of Letters Patent No. 682,794, datedSeptember 17, 1901. Application filed December 19, 1899. Serial No.740,890. (No s ecimens.)

T0 aZZ whom it may concern:

Be it known that I, FRIEDRICH AUGUST GASGH, a subject of the King ofPrussia, German Emperor, residing at Honningen-on-the- Rhine, Prussia,in the Empire of Germany, have invented certain new and usefulImprovements in Processes of Obtaining Zinc Solutions Free from Iron andManganese Compounds, (for which I have applied for patents in England,No. 21,871, dated November 1, 1899; in France, dated September 30, 1899;in Belgium, dated September 29, 1899; in Italy, dated October 29, 1899;in Sweden, dated September 26, 1899; in Norway, dated September 30,1899; in Austria, dated September 25, 1899; in Hungary, dated October11, 1899, and in Germany, dated May 29, 1899,) of which the following isa specification.

This invention relates to a process for preparing zinc solutions freefrom iron and manganesecompounds and at the same time making zinciferousroasted pyrites, by which I mean pyrites from which the sulfur has beenroasted out, profitably useful.

, Hitherto the purification of zinc solutions has been effected byadding to the moderately strong solution chlorid-of-lime solution untilall the iron and manganese are precipitated. The precipitate is so bulkythat mere settling is of no use, and a filter-press has to be employed.Moreoventhe precipitate carries with it much zinc, which is therebylost. By the present invention the roasted pyrites is ground tofragments of about one to two millimeters diameter and intimately mixedwith the quantity of sulfuric acid, of specific gravity Baum, equivalentto the zinc present. This mixture is allowed to remain in heaps for oneto two days, and the product is heated for five to six hours in areverberae-furnac'e at a low red heat. furnace and while it is stillnearly red-hot the material is mixed with a certain proportion of amixture Chile saltpeter or another suitable oxidizing agent and causticlime. By this means the ferrous and manganese compounds present areperoxidized and remain undissolved, being precipitated by the causticlime, when the material is leached with hot water. The followingequations represent this oxidation and precipitation:

Concentrated sulfuric acid is used in this process because it attacksthe iron of the roasted pyrites but little, whereas the dilute acidwhich has been used in other processes easily dissolves the iron.

The process, first, enables zinciferous roasted pyrites to be purifieduntil it contains less than one per cent. of zinc, so thatitis salableas an iron ore j second, doubles the yield of the furnaces, thusreducing the cost for coal and labor, and, third, yields directly a zincsolution free from iron and manganese com pounds, such as isapplicablein some manufacturing processes, without further pu rification.

Instead of concentrated sulfuric acid mixed with common salt a mixtureof ferrous chlorid and concentrated hydrochloric acid may be used.-

What I claim, and desire to secure by Letters Patent of the UnitedStates, is-

1. The process of obtaining zinc solutions substantially free from ironand manganese, which consists in treating zinciferous roasted pyriteswith a strong acid and roasting the product resulting therefrom, andmixing it while still hot with a suitable oxidizing agent and finallyleaching the mixture, substantially as set forth.

2. The process of obtaining zinc solutions substantially free from ironand manganese, which consists in treating zinciferous roasted pyriteswith concentrated sulfuric acid and roasting the product resultingtherefrom at about a temperature of 400 centigrade, and mixing it whilestill hot with a suitable oxidizing agent and finally leaching themixture, substantially as set forth.

In testimony whereof I have hereunto set my hand in the presence of twowitnesses.

FRIEDRICH AUGUST GASCH.

Witnesses HEINRICH GUGGENHEIMER, THERESE ETTL.

